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Excessive fear is a hallmark of anxiety disorders, a major cause of disease burden worldwide. Substantial evidence supports a role of prefrontal cortex-amygdala circuits in the regulation of fear and anxiety, but the molecular mechanisms that regulate their activity remain poorly understood. Here, we show that downregulation of the histone methyltransferase PRDM2 in the dorsomedial prefrontal cortex enhances fear expression by modulating fear memory consolidation. We further show that Prdm2 knock-down (KD) in neurons that project from the dorsomedial prefrontal cortex to the basolateral amygdala (dmPFC-BLA) promotes increased fear expression. Prdm2 KD in the dmPFC-BLA circuit also resulted in increased expression of genes involved in synaptogenesis, suggesting that Prdm2 KD modulates consolidation of conditioned fear by modifying synaptic strength at dmPFC-BLA projection targets. Consistent with an enhanced synaptic efficacy, we found that dmPFC Prdm2 KD increased glutamatergic release probability in the BLA and increased the activity of BLA neurons in response to fear-associated cues. Together, our findings provide a new molecular mechanism for excessive fear responses, wherein PRDM2 modulates the dmPFC -BLA circuit through specific transcriptomic changes. Funding Agencies|Swedish Research Council [2013-07434]; Region ostergotland; Stiftelsen Psykiatriska Forskningsfonden; Wallenberg Foundation; Knut och Alice Wallenberg Stiftelse Grant; Knut and Alice Wallenberg Foundation

beta-catenin-mediated Wnt signaling is an ancient cell-communication pathway in which beta-catenin drives the expression of certain genes as a consequence of the trigger given by extracellular WNT molecules. The events occurring from signal to transcription are evolutionarily conserved, and their final output orchestrates countless processes during embryonic development and tissue homeostasis. Importantly, a dysfunctional Wnt/beta-catenin pathway causes developmental malformations, and its aberrant activation is the root of several types of cancer. A rich literature describes the multitude of nuclear players that cooperate with beta-catenin to generate a transcriptional program. However, a unified theory of how beta-catenin drives target gene expression is still missing. We will discuss two types of beta-catenin interactors: transcription factors that allow beta-catenin to localize at target regions on the DNA, and transcriptional co-factors that ultimately activate gene expression. In contrast to the presumed universality of beta-catenin s action, the ensemble of available evidence suggests a view in which beta-catenin drives a complex system of responses in different cells and tissues. A malleable armamentarium of players might interact with beta-catenin in order to activate the right "canonical" targets in each tissue, developmental stage, or disease context. Discovering the mechanism by which each tissue-specific beta-catenin response is executed will be crucial to comprehend how a seemingly universal pathway fosters a wide spectrum of processes during development and homeostasis. Perhaps more importantly, this could ultimately inform us about which are the tumor-specific components that need to be targeted to dampen the activity of oncogenic beta-catenin. This article is categorized under: Cancer > Molecular and Cellular Physiology Cancer > Genetics/Genomics/Epigenetics Cancer > Stem Cells and Development Funding Agencies|CancerfondenSwedish Cancer Society [CAN 2018/542]; Knut och Alice Wallenbergs StiftelseKnut & Alice Wallenberg Foundation

BCL9 and PYGO are β-catenin cofactors that enhance the transcription of Wnt target genes. They have been proposed as therapeutic targets to diminish Wnt signalling output in intestinal malignancies. Here we find that, in colorectal cancer cells and in developing mouse forelimbs, BCL9 proteins sustain the action of β-catenin in a largely PYGO-independent manner. Our genetic analyses implied that BCL9 necessitates other interaction partners in mediating its transcriptional output. We identified the transcription factor TBX3 as a candidate tissue-specific member of the β-catenin transcriptional complex. In developing forelimbs, TBX3 and BCL9 co-occupy a large number of Wnt-responsive regulatory elements, genome-wide. Moreover, mutations inBcl9affect the expression of TBX3 targets in vivo, and modulation of TBX3 abundance impacts on Wnt target genes transcription in a β-catenin- and TCF/LEF-dependent manner. Finally, TBX3 overexpression exacerbates the metastatic potential of Wnt-dependent human colorectal cancer cells. Our work implicates TBX3 as a new, context-dependent component of the Wnt/β-catenin-dependent enhanceosome.